How to shoot portrait photographs?

I recently purchased a TPVideo1 Camlink forgetting it has no portrait functionality. I have been looking at L-plates but because I use my Nikon D5100 with a battery grip there isn't one that fits, also all the L-plates I have seen have quick release, but it is oriented the wrong way for my tripod.

https://500px.com/...om/lc500px

Added (1). Tripod: https://www.google.co.uk/...xOQ4F9M%3A

It should be a mode under settings on the camera it's self

You have a tripod specifically designed for shooting video, thus no way to rotate the camera into the portrait position.

Here in the States, Kirk makes an "L" bracket that I can use use on my Nikon D800e with battery grip.

Look for "Arca Swiss Type L brackets" on Amazon.co.uk

How difficult is it to hold your dSLR sideways?